Automatic identification (“Auto-ID”) technology is used to help machines identify objects and capture data automatically. One of the earliest Auto-ID technologies was the bar code, which uses an alternating series of thin and wide bands that can be digitally interpreted by an optical scanner. This technology gained widespread adoption and near-universal acceptance with the designation of the Universal Product Code (“UPC”)—a standard governed by an industry-wide consortium called the Uniform Code Council. Formally adopted in 1973, the UPC is one of the most ubiquitous symbols present on virtually all manufactured goods today and has allowed for enormous efficiency in the tracking of goods through the manufacturing, supply, and distribution of various goods.
However, the bar code still requires manual interrogation by a human operator to scan each tagged object individually with a scanner. This is a line-of-sight process that has inherent limitations in speed and reliability. In addition, the UPC bar codes only allow for manufacturer and product type information to be encoded into the barcode, not the unique item's serial number. The bar code on one milk carton is the same as every other, making it impossible to count objects or individually check expiration dates, much less find one particular carton of many.
Currently, retail items are marked with barcode labels. These printed labels have over 40 “standard” layouts, can be mis-printed, smeared, mis-positioned and mis-labeled. In transit, these outer labels are often damaged or lost. Upon receipt, the pallets typically have to broken-down and each case scanned into an enterprise system. Error rates at each point in the supply chain have been 4-18% thus creating a billion dollar inventory visibility problem. However, Radio Frequency Identification (RFID) allows the physical layer of actual goods to automatically be tied into software applications, to provide accurate tracking.
The emerging RFID technology employs a Radio Frequency (RF) wireless link and ultra-small embedded computer chips, to overcome these barcode limitations. RFID technology allows physical objects to be identified and tracked via these wireless “tags”. It functions like a bar code that communicates to the reader automatically without needing manual line-of-sight scanning or singulation of the objects.
Addition of battery power to RFID tags has greatly increased the range in which reliable communication with the tag is possible. This has in turn made new applications possible. One such application is use of RFID tags in an automatic toll payment system. In such a system, an RFID tag having a unique ID that is associated with a vehicle is mounted to the vehicle windshield. When the vehicle passes through a toll lane, the tag identifier is read, correlated with an account, and payment if debited from the account. Thus, the need for a human toll collector is eliminated, as is the need to stop the vehicle at a toll booth. Further, such automated toll lanes are often dedicated to those vehicles having the RFID tag, thereby minimizing toll-collection-related delays.
One drawback of such systems is that the battery does not have an infinite life. Rather, once the battery is dead, the tag must typically be discarded or battery replaced. One solution is to connect the tag to the electrical system of the automobile. However, not only does the automobile need to be retrofitted to provide the power line to the tag, but the tag is then permanently mounted to the vehicle, meaning that if the owner decides to drive another car on the toll road or bridge, the driver must wait in line to pay at a toll booth rather than pass through the automated toll lane.
Another prominent use of battery powered RFID tags is asset tracking during shipment through a supply chain. However, as mentioned above, the life of the battery is not infinite, and so the tag will likely not remain active for the entire life of the object to which coupled. The tag may still respond to queries in a passive mode if it has built in multi-protocols and has C1G2 capability, where the tag is powered by the incoming RF signal, but the range for such communication is severely limited and may not be suitable for applications involving fast moving items such as automobiles, or in situations where an RFID interrogator is not readily available within range of the tag.
The use of liquid electrolyte rechargeable batteries in RFID tags has been contemplated. However, such rechargeable batteries typically provide less power per charge than a comparable disposable battery, and so need to be recharged rather frequently. Unfortunately, such rechargeable batteries do not have a large number of charge/recharge cycles. Rather, such rechargeable batteries lose capacity each time they are recharged, and therefore may only be recharged a handful of times before completely losing the ability to carry a charge sufficient for tag operations.
What are therefore needed are RFID systems and methods for uses such as, but not limited to, asset tracking, ownership transfer tracking and toll collection, which have a greatly improved life span and which overcome the deficiencies in heretofore known systems.